There are already several methods known for the production of low-alcohol or alcohol-free beer. For this purpose, at least a portion of alcohol is removed from beer produced according to conventional brewing processes and having a normal alcohol content. In the method disclosed in the No. DE-A-14 42 238, alcohol is evaporated in a thin layer-evaporator at a temperature below 70 C. In the similar method known from the No. DE-A-12 66 266, beer is firstly subjected to atomisation evaporation in a vacuum and then to thin layer evaporation in a vacuum. The residuals are reblended and impregnated with carbonic acid (carbon dioxide).
Furthermore, the No. DE-A-24 05 543 and the No. DE-A-721 249 describe methods for the adsorptive alcohol removal from beer. A method for the production of low-alcohol beer by reverse osmosis is disclosed in the No. DE-A-23 23 094.
Finally, methods have been proposed in which the alcohol is distilled off in a brewing pan.
On the other hand, methods for the production of low-alcohol or alcohol-free beer have been developed in which the production of alcohol during the production process is reduced from the very beginning.
This is achieved either by using yeast that can only partially ferment wort or by repressing or interrupting fermentation; cf. No. DE-A-520 363 and No. DE-A-728 871.
All the above methods have the disadvantage in that the taste of the low-alcohol or alcohol-free beer obtained thereby is not as good as that of normal alcoholic beer. Beer which is dealcoholised after production is dull and inharmonious in taste, whereas beer in which the production of alcohol is prevented or reduced from the very beginning has the typical, unpleasant taste of wort. It has also been found that the dealcoholisation methods used entail rather high expenditure and are troublesome.
The European patent application No. 183 858, published on 11th June 1986, describes beer, in particular low-alcohol or alcohol-free beer, which is characterised in that it contains 0.3 to 2.0% by volume of glycerol which improves the body of the beer. The method described therein comprises carrying out fermentation via yeast which produces elevated amounts of glycerol and sugar alcohols, the production of ethanol being reduced at the same time.
No fermenting processes in which the production of glycerol is high and that of ethanol extremely low are known.